This paper presents a comprehensive analysis of the dead-time effects in wireless power transfer systems based on LCC-S topology. In these systems operating at high frequencies, the ratio of dead-time versus the operating period becomes critical, and the dead-time issue can cause certain problems regarding power quality, efficiency, and output voltage ripple. The impact of input quantities such as voltage and switching frequency on the efficiency and output power of the LCC-S-tuned WPT system was also investigated. The optimal combination of these parameters used to achieve the maximum efficiency for a target output power and to set the appropriate value of the dead time were determined by running multiple simulations using the MATLAB R2023b software platform. It was also shown that the output voltage remained unchanged with and without a load and up to 1200 ns of dead-time, which provides a simple implementation of the corresponding mathematical model. In the recommended interval of 600–1500 ns, the influence of the dead-time on the value of the output voltage amplitude is less than 10%. The validity of the proposed method was confirmed through the implementation of the experimental prototype, a 5 kW wireless power transmission system, and the obtained results were in accordance with the simulation results.

The most widely adopted category of the mid-range wireless power transmission (WPT) systems is based on the magnetic resonance coupling (MRC), which is appropriate for a very wide range of applications. The primary concerns of the WPT/MRC system design are the power transfer capabilities. Using the scattering parameters based on power waves, the power transfer of an asymmetric WPT/MRC system with the series-series compensation structure is studied in this paper. This approach is very convenient since the scattering parameters can provide all the relevant characteristics of the WPT/MRC system related to power propagation. To maintain the power transfer capability of the WPT/MRC system at a high level, the scattering parameter $S_{21}$ is used to determine the operating frequency of the power source. Nevertheless, this condition does not coincide with the maximum possible power transfer efficiency of the system. In this regard, the WPT/MRC system is thereafter configured with a matching circuit, whereas the scattering parameter $S_{21}^{\prime }$ S21’is used to calculate and then adjust the matching frequency of the system. This results in the maximum available power transfer efficiency and thereby increases the overall performance of the system. Theoretical investigations are followed by numerical simulation and experimental validation.

The design of a wireless power transfer system with double rectangular coils for 11 kW power transfer is considered. System modeling and numerical calculation of the system parameters are described. Coils are made from available Litz wire, which has a smaller than necessary diameter for the required power. Thus, a setup with double layer coils was developed, which resulted in a modified design. Starting from a system consisting of coupled coils, as suggested by the standard for wireless power transfer Level 3 in class Z1, different coil and ferrite shield layouts were tested in numerical simulations, and their parameters were calculated. The prototype was constructed based on the simulated model with the best results and properties. Numerical results were verified by laboratory measurements, and a successful power transfer at 11 kW was achieved.

Wireless power transfer between electric vehicles, based on magnetic coupling, have been proposed and patented by ZF Friedrichshafen AG and Daimler AG. In this system of wireless power transfer, which is categorized as dynamic, the estimation of coupling factor is essential for maximum efficiency tracking. In this paper a novel approach for estimation of coupling factor is proposed. It is based on the coil geometry properties and distance measurement between the electric vehicles.

In inductive power transfer (IPT) systems, the relative position between the primary and secondary side assemblies affects the self-inductance of the coils and their mutual inductance. Additionally, the aging effect of capacitors influences the value of compensation capacitors. It is, therefore, necessary to determine a minimum set of key IPT system parameters when implementing a constant-current (CC) / constant-voltage (CV) battery charging algorithm without real-time communication. This paper presents a method for implementing the CC/CV battery charging algorithm in an LCC-S IPT system without requiring real-time communication or all system parameters. Using only measurements from the primary side, the method is based on the phasor estimation of the primary-side electromotive force (EMF). Estimated parameters include the mutual inductance, the primary-side coil self-inductance and its parasitic resistance, and the secondary-side circuit resonant frequency. The first three parameters are estimated before the battery charging process starts, whereas the secondary-side circuit resonant frequency is identified during the charging process without influencing it. To verify the validity of the proposed method, an IPT prototype with 48 V charging voltage and 4 A charging current is implemented. Experimental results indicate that the estimated parameter set provides fast and accurate output voltage and current control.

This paper explores methods to eliminate high-voltage spikes during dead time ($t_{dt}$) in high-frequency inverters for Wireless Power Transfer (WPT) systems, focusing on the transition from traditional Silicon IGBTs to enhancement-mode Gallium Nitride (GaN) HEMTs. At elevated switching frequencies, dead-time parameters strongly govern system efficiency and signal integrity. While IGBTs suffer from reverse-recovery charge ($Q_{rr}$) in antiparallel freewheeling diodes that generates severe voltage spikes, hard-switching GaN systems require precise dead-time minimization to prevent shoot-through while limiting third-quadrant conduction losses. Unlike prior WPT studies bounded by specific hardware setups, this paper presents a baseline technology benchmark that explicitly decouples intrinsic semiconductor commutation physics, specifically $Q_{rr}=0$ versus third-quadrant conduction, from macro-system parameters ($f_{sw}$, power level, and resonant topology). Experimental evaluation of a 130 kHz L-S-tuned GaN full-bridge inverter confirms that primary current commutates via third-quadrant conduction during dead time, completely eliminating reverse-recovery voltage spikes ($I_{rr}=0$). Ultimately, this work demonstrates that GaN’s spike-free operation is an intrinsic device-level property, reframing the dead-time optimization objective from transient overvoltage suppression to third-quadrant conduction loss minimization in next-generation WPT systems.